The trend in internal combustion engines is to increase efficiency. This has necessitated a move away from engines with fixed, cammed timing towards engines with variable timing, such as is available in camless engines. Instead of the mechanical or mechanical-hydraulic valve train systems of cammed engines, camless engines can use an Electronic Valve Actuator (EVA) and Electro-Hydraulic Valve Actuator (EHA) to operate valves with almost any timing imaginable. However, such electrically dependant valve actuator systems present problems with closure detection and soft landing control. The use of EVA and EHA systems require control and diagnostics of the impact velocity and closure time of the valves. This is required for valve durability, air flow control, and noise, vibration and harshness (NVH) performance.
Impediments to higher volume application of electrically driven (EVA) and electrically actuated and hydraulically driven (EHA) systems is its relatively high system cost. One of the factors causing this high cost is the requirement for closed loop correction of the actuator and using one proximity sensor per actuator. In addition, the support systems for these individual sensors further increase cost because of the number of connectors, wiring, control blocks, integration, etc. required with this approach.
What is needed is lower cost approach for detecting valve closure and operating EHA and EVA valve actuators. In particular, it would be of benefit to provide an apparatus and method of using indirect measurements of valve closure and measuring movements of multiple actuators along with control and diagnostic methods using these measurements.